httpbin(1) - HTTP request and response service
EasyCron - Get frustrated with Cron on your server? Hosting limits your Cron use?
Endpoints - View and respond to requests on an HTTP endpoint
crontab guru - The quick and simple editor for cron schedule expressions by Cronitor
Beew.io - The simplest way of scheduling HTTP requests.
corntab - CRONTAB EDITING MADE SIMPLE